JP2020116029A - Electric water heater - Google Patents

Abstract

To provide an electric water heater capable of reducing the time from when a hot water supply button is depressed to when liquid is discharged in a low speed hot water supply mode, and capable of appropriately pumping up liquid to a discharge port even when cavitation occurs in a pump.SOLUTION: A control unit of an electric water heater can switch a hot water supply mode between a normal hat water supply mode in which a pump is operated at first output and a low speed hot water supply mode in which the pump is operated at second output lower than the first output. When a hot water supply button is depressed in the low speed hot water supply mode, the control unit operates the pump at initial output higher than the second output first (S32). Then, the control unit lowers the output of the pump to the second output before liquid is discharged from the discharge port (S34). Thereby, the time from when the hot water supply button is depressed to when liquid is discharged can be reduced. Also, even when cavitation occurs in the pump, liquid can be appropriately pumped up to the discharge port.SELECTED DRAWING: Figure 5

Description

The present invention relates to an electric water heater that heats a liquid and discharges the heated liquid from a discharge port.

BACKGROUND ART Conventionally, an electric water heater (so-called electric pot) that heats water and discharges heated water (hot water) from a discharge port is known. The electric water heater draws hot water by a pump provided inside and discharges it from a discharge port. Conventional electric water heaters having a pump are described in Patent Documents 1 to 3, for example.

Japanese Patent No. 3494983 Japanese Patent No. 5076577 Japanese Patent No. 3543785

Some electric water heaters have a normal hot water supply mode and a low speed hot water supply mode. In the low-speed hot water supply mode, the pump is operated at a low output to discharge hot water from the discharge port at a lower speed than in the normal hot water supply mode. Such a low-speed hot water supply mode is used, for example, when extracting drip coffee.

However, in the conventional low-speed hot water supply mode, it takes time to pump hot water because the output of the pump is low. Therefore, there is a problem that it takes a long time until the hot water is discharged from the discharge port after the user presses the hot water supply button.

Further, inside the pump in the electric water heater, a negative pressure locally generated may cause bubbles (cavitation) of steam. When the output of the pump is low, it becomes difficult to pump hot water well due to the influence of this cavitation. As a result, there is a problem that the performance of discharging hot water from the discharge port may deteriorate.

The present invention has been made in view of such circumstances, and in the low-speed hot water supply mode, it is possible to shorten the time from pressing the hot water supply button until the liquid is discharged, and when cavitation occurs in the pump. Another object is to provide an electric water heater capable of satisfactorily pumping liquid up to the discharge port.

The electric water heater of the present invention comprises a container for storing a liquid therein, a heater for heating the liquid in the container, a discharge port for discharging the heated liquid, a bottom portion of the container and the discharge port. A connecting discharge pipe, a pump for sending the liquid in the container to the discharge port through the discharge pipe, a hot water supply button for receiving a hot water supply instruction, and a control unit for controlling the operation of the pump, The control unit can switch between a normal hot water supply mode in which the pump operates at the first output and a low-speed hot water supply mode in which the pump operates at a second output lower than the first output. In the low-speed hot water supply mode, When the hot water supply button is pressed, first, the pump is operated at an initial output higher than the second output, and thereafter, before the liquid is discharged from the discharge port, the output of the pump is changed to the first output. Reduce to 2 outputs.

In this electric water heater, in the low-speed hot water supply mode, the time from pressing the hot water supply button to discharging the liquid can be shortened. Further, even when cavitation occurs in the pump, the liquid can be satisfactorily pumped up to the discharge port.

In particular, it is preferable that in the low speed hot water supply mode, the control unit gradually or gradually lowers the output of the pump from the initial output to the second output. This can prevent the shape of the liquid discharged from the discharge port from being disturbed. Further, the change in the motor sound due to the change in the output of the motor also becomes gentle. Therefore, it is possible to reduce the discomfort of the sound perceived by the user.

Further, the initial output is preferably the same output as the first output. As a result, if the first output, which is the output in the normal hot water supply mode, is designed so that the liquid can be satisfactorily sent, the liquid can be satisfactorily sent even in the initial output immediately after pressing the hot water supply button in the low-speed hot water supply mode. You can

In addition, it is preferable that the second output within a predetermined time after completion of the water heating is higher than the second output after the predetermined time has elapsed. This makes it possible to further suppress the deterioration of the ejection performance due to cavitation immediately after the completion of boiling water.

Further, it is preferable that the initial output within a predetermined time after the completion of boiling is higher than the initial output after the predetermined time has elapsed. This makes it possible to further suppress the deterioration of the ejection performance due to cavitation immediately after the completion of boiling water.

Further, the time for operating the pump at the initial output is longer than the time required for pumping the liquid in the discharge pipe when the amount of liquid stored in the container is the minimum amount, and/or the inside of the container When the stored amount of the liquid is the maximum amount, it is preferable that the time is shorter than the time required to send the liquid to the ejection port. As a result, the liquid can be satisfactorily pumped and discharged regardless of the amount of the liquid stored in the container.

According to the present invention, in the low-speed hot water supply mode, the time from pressing the hot water supply button to discharging the liquid can be shortened. Further, even when cavitation occurs in the pump, the liquid can be satisfactorily pumped up to the discharge port.

It is a side view of an electric water heater. It is a side view of an electric water heater with a pot body and a lid omitted. It is a top view of an operation panel. It is the block diagram which showed the electric connection of the control part and each part in an electric water heater. It is the flowchart which showed the flow of the hot water supply operation in the electric water heater. 6 is a graph showing a change over time in the electric power supplied to the pump after the hot water supply button is pressed in the normal hot water supply mode. 7 is a graph showing a change over time in the electric power supplied to the pump after the hot water supply button is pressed in the low speed hot water supply mode. It is the figure which showed the 1st modification of the graph of FIG. It is the figure which showed the 2nd modification of the graph of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<1. Structure of electric water heater>
FIG. 1 is a side view of an electric water heater 1 according to an embodiment of the present invention. FIG. 2 is a side view of the electric water heater 1 with the pot body 10 and the lid 30 omitted. The electric water heater 1 is a so-called electric pot that heats liquid water and discharges heated water (hot water) from the discharge port 14. As shown in FIGS. 1 and 2, the electric water heater 1 according to the present embodiment includes a pot body 10, an inner container 20, a lid 30, a heater 40, a discharge pipe 50, a pump 60, an operation panel 70, and a controller. Equipped with 80.

The pot body 10 is a housing made of synthetic resin. The pot main body 10 has a pot bottom portion 11, a cylindrical pot side wall portion 12 extending upward from an edge of the pot bottom portion 11, and an eaves portion 13 protruding forward from an upper end portion of the pot side wall portion 12. .. The inner container 20, the heater 40, the discharge pipe 50, the pump 60, and the control unit 80 are housed in the internal space of the pot body 10 and fixed directly or indirectly to the pot body 10. The pot body 10 may be provided with a handle that the user holds when transporting the electric water heater 1.

The inner container 20 is a container made of stainless steel that stores therein water or hot water. The inner container 20 has a container bottom portion 21 and a cylindrical container side wall portion 22 extending upward from the edge of the container bottom portion 21. A heat insulating layer may be provided outside the inner container 20 in order to improve heat retention. Further, the inner container 20 itself may have a vacuum double structure. A scale line 23 indicating the storage amount of water or hot water is displayed on the inner peripheral surface of the container side wall portion 22.

The lid 30 is rotatably connected to the pot body 10 by a hinge 15 provided on the rear portion of the pot body 10. As shown by an arrow A in FIG. 1, the lid 30 is between a horizontal posture (the posture of FIG. 1) that covers the upper portion of the pot body 10 and a standing posture that stands substantially vertically with respect to the pot body 10. It rotates about the hinge 15. When the lid body 30 is in the horizontal posture, the upper opening of the inner container 20 is closed by the lid body 30. When the lid 30 is in the upright posture, the upper portion of the inner container 20 is opened, and water can be replenished into the inner container 20.

The lid 30 is provided with a knob portion 31 that the user holds when opening and closing, and a steam port 32 for discharging the steam in the inner container 20 to the outside.

The heater 40 is a means for heating and keeping the water in the inner container 20 warm. The heater 40 is arranged on the lower surface of the container bottom portion 21 of the inner container 20. As the heater 40, for example, a mica heater or a sheath heater is used. When the electric water heater 1 is used, electric power is supplied from the control unit 80 to the heater 40. As a result, the heater 40 generates heat and the water in the inner container 20 is heated to be hot water. It should be noted that a heater for heating water at room temperature and a heater for keeping the hot water after heating may be separately provided.

The discharge pipe 50 is a pipe that connects the container bottom portion 21 of the inner container 20 and the discharge port 14 provided on the lower surface of the eaves portion 13. The discharge pipe 50 extends vertically upward along the outer peripheral surface of the container side wall 22 in front of the inner container 20. The inside of the discharge pipe 50 serves as a flow path for sending the hot water from the inner container 20 to the discharge port 14 when the hot water is discharged.

The pump 60 is a means for sending the hot water in the inner container 20 to the discharge port 14 via the discharge pipe 50. The pump 60 is provided near the connecting portion between the container bottom portion 21 and the discharge pipe 50. The pump 60 has a casing that temporarily stores hot water, blades arranged in the casing, and a motor that rotates the blades. The motor rotates the blade according to the electric power supplied from the control unit 80. As a result, the hot water in the inner container 20 is sent to the discharge port 14 via the discharge pipe 50, and the hot water is discharged from the discharge port 14.

The operation panel 70 is provided on the upper surface of the eaves portion 13. FIG. 3 is a top view of the operation panel 70. As shown in FIG. 3, the operation panel 70 has a liquid crystal display 71 and a plurality of buttons. On the liquid crystal display unit 71, various information such as the temperature of hot water in the inner container 20 is displayed. The plurality of buttons include a mode switching button 72 and a hot water supply button 73. Mode switching button 72 is a button for receiving a hot water supply mode switching instruction. Hot water supply button 73 is a button for receiving an instruction for a hot water supply operation.

The control unit 80 is means for controlling the operation of each unit of the electric water heater 1. The control unit 80 is composed of, for example, a circuit board on which a microcomputer is mounted. FIG. 4 is a block diagram showing the electrical connection between the control unit 80 and each unit in the electric water heater 1. As shown in FIG. 4, the controller 80 is electrically connected to the heater 40, the pump 60, and the operation panel 70 described above. The control unit 80 supplies electric power to the heater 40 and the pump 60 based on a command signal supplied from the operation panel 70 and a preset program. As a result, the operations of the heater 40 and the pump 60 are controlled. As a result, the boiling water operation and the hot water supply operation are executed.

<2. Hot water supply>
Next, the hot water supply operation of the electric water heater 1 will be described. FIG. 5 is a flowchart showing a flow of hot water supply operation in the electric water heater 1.

The control unit 80 of the electric water heater 1 can switch between two modes of a normal hot water supply mode and a low speed hot water supply mode. The normal hot water supply mode is a mode in which the pump 60 is operated at the first output to discharge a normal amount of hot water from the discharge port 14. The low speed hot water supply mode is a mode in which the pump 60 is operated at a second output lower than the first output to discharge hot water from the discharge port 14 at a low speed. The low-speed hot water supply mode is suitable, for example, when extracting drip coffee.

In the initial state, control unit 80 is set to the normal hot water supply mode. Unless the user presses the mode switching button 72 (step S1: no), the control unit 80 is maintained in the normal hot water supply mode (step S2). However, when the user presses the mode switching button 72 (step S1: yes), the control unit 80 switches from the normal hot water supply mode to the low speed hot water supply mode (step S3).

FIG. 6 is a graph showing changes over time in the electric power supplied to pump 60 after pressing hot water supply button 73 in the normal hot water supply mode. The horizontal axis of FIG. 6 indicates the elapsed time after the hot water supply button 73 is pressed. The vertical axis of FIG. 6 indicates the electric power supplied to the pump 60.

When hot water supply button 73 is pressed in the normal hot water supply mode (step S21: yes), control unit 80 supplies constant first electric power W1 to pump 60, as shown in FIG. Then, the pump 60 operates at a constant first output (step S22). Thereby, the hot water in the inner container 20 is sent to the discharge pipe 50. Then, hot water is discharged from the discharge port 14. Eventually, when the pressing of the hot water supply button 73 is released (step S23: yes), the control unit 80 stops the supply of the first electric power W1 and stops the pump 60 (step S24).

FIG. 7 is a graph showing changes over time in the electric power supplied to pump 60 after pressing hot water supply button 73 in the low-speed hot water supply mode. The horizontal axis of FIG. 7 indicates the elapsed time after pressing the hot water supply button 73. The vertical axis of FIG. 7 indicates the electric power supplied to the pump 60.

When the hot water supply button 73 is pressed in the low speed hot water supply mode (step S31: yes), the control unit 80 first supplies a constant initial power Ws to the pump 60, as shown in FIG. As a result, the pump 60 is operated at the initial output (step S32). The initial power Ws is higher than the second power W2 described later. In the present embodiment, the initial electric power Ws is the same electric power as the above-described first electric power W1. However, the initial power Ws may be higher than the first power W1 or may be slightly lower than the first power W1.

The operation time Ts of the pump 60 at the initial output is preset in the control unit 80. After pressing hot water supply button 73, control unit 80 continues the operation of pump 60 at the initial output until the operation time Ts elapses (step S33: no). As a result, the hot water in the inner container 20 is pumped up to a position in front of the discharge port 14 in the discharge pipe 50.

When the preset operation time Ts elapses after pressing the hot water supply button 73 (step S33: yes), the control unit 80 reduces the electric power supplied to the pump 60 from the initial electric power Ws to the second electric power W2. As a result, the output of the pump 60 is reduced from the initial output to the second output (step S34). At this time, the electric power supplied to the pump 60 is gradually reduced continuously or stepwise.

After that, the control unit 80 maintains the power supplied to the pump 60 at the second power W2. This causes the pump 60 to operate at the second output. As a result, hot water is discharged from the discharge port 14 of the electric water heater 1 at a lower speed than in the normal hot water supply mode. Eventually, when the pressing of the hot water supply button 73 is released (step S35: yes), the control unit 80 stops the supply of the second power W2 to the pump 60 (step S36).

As described above, in the electric water heater 1, in the low-speed hot water supply mode, immediately after the hot water supply button 73 is pressed, the pump 60 is operated at an initial output higher than the second output. As a result, the time from pressing the hot water supply button 73 to discharging hot water can be shortened.

Further, in the casing of the pump 60, the hot water may be vaporized due to the local negative pressure caused by the rotation of the blades, and vapor bubbles (cavitation) may be generated. When cavitation occurs, it may be difficult to pump hot water, especially when the output of the pump 60 is low. However, in this electric water heater 1, in the low-speed hot water supply mode, immediately after the hot water supply button 73 is pressed, the pump 60 is operated at an initial output higher than the second output. Therefore, even when cavitation occurs, hot water can be pumped up to the discharge port 14 well. As a result, defective discharge of hot water in the low-speed hot water supply mode can be suppressed.

In particular, in the electric water heater 1 of the present embodiment, in the low speed hot water supply mode, the output of the pump 60 is not gradually reduced from the initial output to the second output, but is gradually or gradually reduced. With this configuration, the output of the pump 60 can be reduced while suppressing the shape of the hot water discharged from the discharge port 14 from being disturbed. Further, the change in the motor sound due to the change in the output of the motor also becomes gentle. Therefore, it is possible to reduce the discomfort of the sound perceived by the user.

Further, in the present embodiment, the initial output in the low speed hot water supply mode is the same output as the first output in the normal hot water supply mode. Therefore, if the hot water is pumped well at the first output which is the output of the normal hot water supply mode, the hot water can be pumped well even at the initial output immediately after pressing the hot water supply button in the low speed hot water supply mode. it can. This facilitates the design of the electric water heater 1.

If the operation time Ts for operating the pump 60 at the initial output is too short, it becomes difficult to pump hot water through the discharge pipe 50. On the other hand, if the operation time Ts for operating the pump 60 at the initial output is too long, hot water will be discharged from the discharge port 14 with the initial output higher than the second output. The time from the start of the operation of the pump 60 until the hot water is discharged also varies depending on the amount of hot water stored in the inner container 20.

Therefore, the operation time Ts at the initial output is the discharge pipe when the stored amount of hot water in the inner container 20 is the minimum amount (for example, the minimum amount indicated by the scale line 23 on the inner peripheral surface of the container side wall portion 22). When it is longer than the time required to pump hot water in 50 and/or the stored amount of hot water in the inner container 20 is the maximum amount (for example, the maximum amount indicated by the scale line 23 on the inner peripheral surface of the container side wall portion 22). In addition, it may be set to be shorter than the time required to send the hot water to the discharge port 14. With this configuration, the hot water can be satisfactorily pumped and discharged regardless of the amount of the hot water stored in the inner container 20.

<3. Modification>
Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

<3-1. First Modification>
FIG. 8 is a diagram showing a first modification of the graph of FIG. In this modification, when the hot water supply button 73 is pressed within a predetermined time ΔT after completion of boiling water, the power change of FIG. 8A is applied. On the other hand, when the hot water supply button 73 is pressed after the elapse of the predetermined time ΔT after the completion of boiling, the electric power change of FIG. 8B is applied. The difference between FIG. 8A and FIG. 8B is the magnitude of the second electric power W2. The second electric power W2 in FIG. 8A is larger than the second electric power W2 in FIG. 8B. For example, the second electric power W2 in FIG. 8A is 70% of the first electric power W1, and the second electric power W2 in FIG. 8B is 60% of the first electric power W1. That is, in the present modification, the second output within the predetermined time ΔT after completion of the water heating is higher than the second output after the predetermined time ΔT has elapsed. The predetermined time ΔT may be set to about 1 minute and 30 seconds, for example.

The temperature of the hot water within a predetermined time ΔT after completion of boiling is extremely close to 100°C. When the pump 60 is operated in this state, the above-mentioned cavitation is particularly likely to occur. However, in the example of FIG. 8, in the low-speed hot water supply mode, when the hot water supply button 73 is pressed within the predetermined time ΔT after completion of boiling water, the pump 60 can be operated at a higher second output. Therefore, it is possible to further suppress the deterioration of the ejection performance due to cavitation.

In the present modification, the second output is changed in two steps before and after the predetermined time ΔT has passed, but the second output may be changed in more steps over time. ..

<3-2. Second Modification>
FIG. 9 is a diagram showing a second modification of the graph of FIG. In this modification, when the hot water supply button 73 is pressed within a predetermined time ΔT after completion of boiling water, the power change of FIG. 9A is applied. On the other hand, when the hot water supply button 73 is pressed after the elapse of the predetermined time ΔT after the completion of boiling, the electric power change of FIG. 9B is applied. The difference between FIG. 9A and FIG. 9B is the magnitude of the initial power Ws and the second power W2. The initial power Ws in FIG. 9A is larger than the initial power Ws in FIG. 9B. Further, the second electric power W2 in FIG. 9A is larger than the second electric power W2 in FIG. 9B.

That is, in the present modification, the initial output within the predetermined time ΔT after completion of boiling water is higher than the initial output after the predetermined time ΔT has elapsed. Further, the second output within the predetermined time ΔT after the completion of the boiling is higher than the second output after the predetermined time ΔT has elapsed.

With this configuration, in the low-speed hot water supply mode, when the hot water supply button 73 is pressed within the predetermined time ΔT after completion of boiling water, the pump 60 can be operated not only by the second output but also by increasing the initial output. it can. Therefore, it is possible to further suppress the deterioration of the ejection performance due to cavitation.

In this modification, the initial output and the second output are changed in two stages before and after the predetermined time ΔT has passed, but the initial output and the second output are increased more with the passage of time. It may be changed in stages.

<3-3. Other modifications>
The electric water heater 1 of the above embodiment has two hot water supply modes, a normal hot water supply mode and a low speed hot water supply mode. However, the electric water heater of the present invention may further have another hot water supply mode.

In the above embodiment, the output of the pump 60 is controlled by the electric power supplied to the pump 60. This electric power is controlled, for example, by changing the voltage value. However, the power may be controlled by changing the duty ratio of the PWM signal. In addition, each value and ratio of power, output, and time in the above-described embodiment is merely an example. These respective values and ratios may be appropriately set according to conditions such as the shape and size of the electric water heater 1.

Further, in the above embodiment, the liquid stored in the electric water heater 1 was water. However, the liquid stored in the electric water heater 1 may be another liquid such as tea.

Further, the detailed shape of the electric water heater may be different from the drawings of the present application. Further, the respective elements appearing in the above-described embodiments and modified examples may be appropriately combined as long as no contradiction occurs.

DESCRIPTION OF SYMBOLS 1 Electric water heater 10 Pot main body 11 Pot bottom part 12 Pot side wall part 13 Eaves part 14 Discharge port 15 Hinge 20 Inner container 21 Container bottom part 22 Container side wall part 23 Scale line 30 Lid body 31 Knob part 32 Steam port 40 Heater 50 Discharge pipe 60 pump 70 operation panel 71 liquid crystal display 72 mode switching button 73 hot water supply button 80 controller Ts operating time W1 first power W2 second power Ws initial power ΔT predetermined time

Claims (6)

A container for storing liquid inside,
A heater for heating the liquid in the container,
A discharge port for discharging the heated liquid,
A discharge pipe connecting the bottom of the container and the discharge port,
A pump for sending the liquid in the container to the discharge port through the discharge pipe,
A hot water supply button that accepts hot water supply instructions,
A control unit for controlling the operation of the pump,
An electric water heater equipped with
The control unit is
A normal hot water supply mode in which the pump is operated at the first output,
A low-speed hot water supply mode in which the pump is operated at a second output lower than the first output,
Can be switched to
In the low speed hot water supply mode,
When the hot water supply button is pressed, first, the pump is operated at an initial output higher than the second output, and thereafter, before the liquid is discharged from the discharge port, the pump output is changed to the second output. An electric water heater that reduces the output. The electric water heater according to claim 1,
The control unit is
An electric water heater that gradually or gradually decreases the output of the pump from the initial output to the second output in the low-speed hot water supply mode. The electric water heater according to claim 1 or 2,
The electric water heater, wherein the initial output is the same output as the first output. The electric water heater according to any one of claims 1 to 3,
An electric water heater in which the second output within a predetermined time after completion of boiling water is higher than the second output after the predetermined time has elapsed. The electric water heater according to any one of claims 1 to 4,
An electric water heater in which the initial output within a predetermined time after completion of boiling water is higher than the initial output after the predetermined time has elapsed. The electric water heater according to any one of claims 1 to 5,
The time for which the pump is operated at the initial output is longer than the time required for pumping the liquid in the discharge pipe when the storage amount of the liquid in the container is the minimum amount, and/or the liquid in the container. The electric water heater having a maximum storage amount of less than the time required to send the liquid to the discharge port.

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